Wet shield for a cryogenic vessel

ABSTRACT

The inner shell of a cryogenic storage container is surrounded by a wet shield for intercepting heat before it can enter the inner-shell. The wet shield comprises a plurality of shielding tanks which are mounted side-by-side around the inner-shell for receiving and retaining respective quantities of a shielding cryogenic fluid. Each of the tanks are made up of elongated flat extruded tubes joined together by butt welds and interconnected at their ends by interconnecting pipes. A lower tank surrounds approximately the lower 180* portion of the inner-shell, while right and left upper tanks surround the respective upper right and left 90* portions of the inner-shell container. An inlet line is attached at the bottom of the lower tank, and upper ends of the lower tank communicate with the upper ends of the right and left upper tanks via lower tank vent lines. In addition, the lower ends of the right and left upper tanks are interconnected by an upper-tank interconnecting line; and the upper portions of the right and left upper tanks are connected to vent lines.

United States Patent [191 McIntosh et al.

1 July 22,1975

[ WET SHIELD FOR A CRYOGENIC VESSEL [75] Inventors: Glen E. McIntosh; John D. Loudon,

both of Boulder, C010.

[73] Assignee: Cryenco, Denver, Colo.

[22] Filed: Mar. 22, 1974 [21] Appl. No.: 453,811

[52] US. Cl. 62/45; 220/9 LG Primary ExaminerWilliam F. ODea Assistant ExaminerRonald C. Capossela Attorney, Agent, or FirmGriffin, Branigan & Butler [57] ABSTRACT The inner shell of a cryogenic storage container is surrounded by a wet shield for intercepting heat before it can enter the inner-shell. The wet shield comprises a plurality of shielding tanks which are mounted sideby-side around the inner-shell for receiving and retaining respective quantities of a shielding cryogenic fluid. Each of the tanks are made up of elongated flat extruded tubes joined together by butt welds and interconnected at their ends by interconnecting pipes. A lower tank surrounds approximately the lower 180 portion of the inner-shell, while right and left upper tanks surround the respective upper right and left 90 portions of the inner-shell container. An inlet line is attached at the bottom of the lower tank, and upper ends of the lower tank communicate with the upper ends of the right and left upper tanks via lower tank vent lines. In addition, the lower ends of the right and left upper tanks are interconnected by an upper-tank interconnecting line; and the upper portions of the right and left upper tanks are connected to vent lines.

13 Claims, 6 Drawing Figures SHEET PATENTED JUL 2 2 ms PATENTEDJUL22 m5 3.895197 SHEET 2 LEFT UPPER RIGHT UPPER I? SHIELDING SHIELDING TANK TANK LOWER SHIELDING TANK WET SHIELD FOR A CRYOGENIC VESSEL BACKGROUND OF THE INVENTION This invention relates broadly to the art of cryogenic vessels and more particularly to the art of refrigeration shields for such vessels.

It is common practice in the storage of cryogenic liq-- uids, particularly in the storage of liquid helium, to employ liquid-nitrogen-cooled shields to intercept heat before it can enter inner-shells of the containers. In the past, this has been accomplished by employing a separate storage container for storing liquid nitrogen and continually passing nitrogen from the storage container through tubes attached to shield. In this arrangement, the separate, liquid-nitrogen container takes up an unduly large amount of space. Such wasted space is particularly troublesome with truck mounted cryogenic vessels which are limited in size in order to meet highway requirements. Thus, it is an object of this invention to provide a refrigeration shielded vessel which makes better use of available space.

It is another object of this invention to provide a refrigeration shielded vessel which not only conserves space, but which distributes cryogenic shielding fluid relatively uniformly about the cryogenic vessel.

It is a further object of this invention to provide an interconnecting system for filling the refrigeration shielding systems storage tanks of a cryogenic vessel and for allowing proper venting of these tanks.

SUMMARY OF THE INVENTION According to principles of this invention, a cryogenic vessels refrigeration shielding system comprises a plurality of shielding tanks or wet shields dispersed about an inner storage vessel or shell. The wet-shield tanks each comprise a plurality of elongated, flat tubes which are joined together along their side edges by butt welds and which are joined at their ends by manifolding pipes.

The shielding tanks are mounted side-by-side around the containers inner-shell with one tank covering approximately the lower l80 portion of the inner vessel, an upper right shielding tank covering approximately the upper right 90 portion of the inner vessel and an upper left shielding tank covering approximately the upper left 90 portion of the inner vessel.

An interconnecting assembly includes an inlet line connected to the bottom of the lower shielding tank; left and right lower-tank vent lines interconnecting upper portions of the lower shielding tank with upper portions of the right and left upper tanks; and left and right upper tank vent lines connected to upper portions of the right and left upper tanks.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in accompanying drawings in which reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention in a clear manner.

FIG. 1 is an isometric, partially schematic, view of the inner portions of a truck-mountable cryogenic vesse] including a wet shield employing principles of this invention;

FIG. 2 is an end view of the cryogenic vessel of FIG.

FIG. 3 is a sectional view of a portion of the wet shield of FIGS. 1 and 2;

FIG. 4 is an enlarged plan view of a portion of the cryogenic shield of FIGS. 1 and 2;

FIG. 5 is a sectional view taken on line 55 in FIG. 4; and

FIG. 6 is a schematic flow diagram of the shielding tanks of the FIGS. 1 and 2 wet shield.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2, the inner portions of a cryogenic vessel 11 basically includes an inner shell container 13 with associated tubing 15, an outer wet shield'17, with associated manifolding tubing to be described below, and mounts 19 for mounting the vessels. inner portions within the customary outer shell. I

A cryogenic liquid, such as helium, can be stored in the inner-shell container 13 which includes the usual schematically illlustrated inlet and vent tubing 15. Likewise, the mounts 19 are intended to suspend the vessels inner structure within its outer shell. It is not thought necessary to describe these elements in greater detail as they are not important features of the invention.

The wet shield 17 comprises a multiplicity of extruded metallic tubes 21 which are joined together by butt welds in such a manner that, taken together, they form tanks or a wet shield. FIG. 3 depicts a crosssection of one of these tubes 21a which is welded to tubes 21b and 210 at welds 23 and 25 which run the length of the shield. Partitions 27 in the middle of the tubes 21 strengthen the tubes to withstand the required large internal pressures. Weld adapters 29 are inserted between the tubes 21, and welded thereto by the welds 23 and 25, to provide a spacing which produces a contour such that when all of the required tubes are welded together, they form a cylinder having the diameter of the desired shield. It can also be seen in FIGS. 1, 2 and 5 that the weld adapters 29 are welded to an aft shield 31 at weld 33; and, they are also welded to a fore shield (not shown). The aft shield 31 surrounds an aft end of cover the right and left upper 90 portions of the cryogenic vessel 11.

A shielding-tank interconnecting system includes a cryogenic fluid inlet line 43 having a main inlet valve 45 and an auxiliary inlet valve 47. Cryogenic fluid passjjing through the main inlet valve 45 enters the lower shielding tank 37 at its lowermost position; and cryogenic fluid passing through the auxiliary valve 47 enters the right upper shielding tank 39 at its lowermost portion. Right and left lower-tank vent lines 49 and 51 respectively interconnect right and left upper portions of the lower shielding tank 37 with upper portions of the right and left upper shielding tanks 39 and 41. An upper-tank interconnection line 53 interconnects lower portions of the right and left upper shielding tanks 39 and 41. Right and left upper tank vent lines 55 and 57 allow spent gases to vent from the right and left upper shielding tanks 39 and 41 to a final vent line 59.

A laminated insulation 60 encloses the entire cryogenic vessel 11, however, for the sake of clarity only a small portion of this element is depicted in FIG. 1.

Operation of the wet shield 17 is described with reference to the schematic diagram of FIG. 6. Therein, the wet shield 17 is activated by inserting under pressure a cryogenic shielding liquid, such as liquid nitrogen, in the inlet line 43. Normally, during insertion, the main inlet valve 45 is set in an open position and the auxiliary valve 47 is maintained in a closed position; thus, the cryogenic shielding fluid flows only into the lower shielding tank 37. Spent gases given off therefrom rise through the right and left lower-tank vent lines 49 and 51 into the right and left upper shielding tanks 39 and 41 and thence out the right and left upper-tank vent lines 55 and 57 to the final vent line 59.

When the lower shielding tank 37 is full of cryogenic shielding liquid, the liquid will rise in the right and left lower-tank vent lines 49 and 51 and spill into the right and left upper shielding tanks 39 and 41. The liquid levels in the right and left upper shielding tanks 39 and 41 will be substantially the same since liquid flows through the uppertank interconnection line 53. When all of the shielding tanks are full, liquid will exit via the vent lines 55 and 57. The main inlet valve 45 is then closed.

The auxiliary valve 47 and its associated inlet line are not really necessary to this invention. This valve can be opened to fill only the upper shielding tanks or to fill both the upper and lower shielding tanks simultaneously if it is so desired; or it can be used to drain the upper shielding tanks in the event the vessel is to be taken out of service for storage or repair.

The cryogenic shielding fluid in the upper and lower shielding tanks cools these metallic tanks to intercept heat before it can reach the inner-shell 13 (FIG. 1). Over a period of time, the cryogenic shielding liquid gasifies with spent gases passing through the vents 49, 51, 55, 57 and 59. Thus, the levels of liquid in the respective tanks lowers with the passage of time. The upper shielding tanks 39 and 41 and the lower shielding tank 37 are sized so that their liquid levels will change at substantially the same rate. Thus, when the reservoirs are nearly empty, the farthest distance from a liquid point to a point having no liquid will be about onefourth of the circumference of the cryogenic vessel 11.

It has been found that by use of this invention, the capacity of the inner-shell 13 can be substantially increased for truck mounted units. In this regard, a conventional unit which previously had a capacity of 9,200 gallons has had its capacity increased by structure of this invention to 10,800 gallons. This capacity increase is obtained by eliminating previously used spacewasting, separate, cryogenic shielding-fluid containers. Similarly, without any increase in overall size, the structure of the invention permits an increase in the amount of refrigeration fluid that can be stored. In the vessel just discussed, for example, not only was the inner shells fluid capacity increased by 1,600 gallons, but the capacity for refrigeration fluid was increased from 500 gallons to 700 gallons.

In addition, this invention provides a sleeve-type wet shield which is uniformly effective about a cryogenic vessel and which is sufficiently strong to withstand the required pressures.

Moreover, this invention provides an uncomplicated interconnecting system for filling and venting a plurality of shielding tanks located about a cryogenic vessel.

While this invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, the number of shielding tanks could be increased to provide a more even distribution of cryogenic shielding liquid.

The embodiments of the invention in which an exclusive property or privilege are claimed are defined as follows:

1. A wet shield cryogenic fluid container comprising:

an inner-shell means for receiving and storing cryoa wet shield surrounding said inner-shell, said wet shield comprising:

shielding tank means for receiving and storing a quantity of a cryogenic shielding liquid to intercept heat, said shielding tank means including a plurality of shielding tanks mounted side-by-side around said inner shell; and,

an interconnecting assembly means for supplying said cryogenic shielding liquid to said plurality of shielding tanks and for venting spent gases from each of said shielding tanks at an upper portion thereof, whereby said cryogenic shielding liquid is retained in pockets radially positioned about said inner-shell container.

2. A wet-shield cryogenic fluid container as claimed in claim 1 wherein said interconnecting assembly includes a means for filling said plurality of shielding tanks from a single inlet tube.

3. A wet-shield cryogenic fluid container as claimed in claim 2 wherein said inlet tube communicates with a lower portion of a lower shielding tank and wherein an upper portion of said lower shielding tank communicates with upper portions of other shielding tanks.

4. A wet-shield cryogenic fluid container as claimed in claim 3 wherein upper portions of all of said plurality of shielding tanks have vents for allowing spent gases to be vented therefrom.

5. A wet-shield cryogenic fluid container as claimed in claim 1 wherein a lowermost shielding tank is located adjacent the lower portion of said inner-shell, and right and left upper shielding tanks respectively are located adjacent right and left upper portions of said inner-shell.

6. A wet-shield cryogenic fluid container as claimed in claim 5 wherein said interconnecting assembly includes a means for filling said plurality of shielding tanks from a single inlet tube.

7. A wet-shield cryogenic fluid container as claimed in claim 6 whereinsaid inlet tube communicates with a lower portion of a lower shielding tank and wherein an upper portion of said lower shielding tank communicates with upper portions of other shielding tanks.

8. A wet-shield cryogenic fluid container as claimed in claim 7 wherein upper portions of all of said plurality of shielding tanks have vents to allow spent gases to be vented therefrom.

9. A wet-shield cryogenic fluid container as claimed in claim 1 wherein each of said tanks comprises elongated, flat tubes which are attached to one another in a side-by-side relationship and which are interconnected with one another by pipes located at the ends of said tubes.

10. A wet-shield cryogenic fluid container as claimed in claim 9 wherein a lower shielding tank covers the lower portion of said inner-shell, and right and left upper shielding tanks respectively cover right and left upper portions of said inner-shell.

11. A wet-shield cryogenic fluid container as claimed in claim 10 wherein said manifold assembly includes be vented therefrom. 

1. A wet shield cryogenic fluid container comprising: an inner-shell means for receiving and storing cryogenic fluids; a wet shield surrounding said inner-shell, said wet shield comprising: shielding tank means for receiving and storing a quantity of a cryogenic shielding liquid to intercept heat, said shielding tank means including a plurality of shielding tanks mounted side-by-side around said inner shell; and, an interconnecting assembly means for supplying said cryogenic shielding liquid to said plurality of shielding tanks and for venting spent gases from each of said shielding tanks at an upper portion thereof, whereby said cryogenic shielding liquid is retained in pockets radially positioned about said innershell container.
 2. A wet-shield cryogenic fluid container as claimed in claim 1 wherein said interconnecting assembly includes a means for filling said plurality of shielding tanks from a single inlet tube.
 3. A wet-shield cryogenic fluid container as claimed in claim 2 wherein said inlet tube communicates with a lower portion of a lower shielding tank and wherein an upper portion of said lower shielding tank communicates with upper portions of other shielding tanks.
 4. A wet-shield cryogenic fluid container as claimed in claim 3 wherein upper portions of all of said plurality of shielding tanks have vents for allowing spent gases to be vented therefrom.
 5. A wet-shield cryogenic fluid container as claimed in claim 1 wherein a lowermost shielding tank is located adjacent the lower portion of said inner-shell, and right and left upper shielding tanks respectively are located adjacent right and left upper portions of said inner-shell.
 6. A wet-shield cryogenic fluid container as claimed in claim 5 wherein said interconnecting assembly includes a means for filling said plurality of shielding tanks from a single inlet tube.
 7. A wet-shield cryogenic fluid container as claimed in claim 6 wherein said inlet tube communicates with a lower portion of a lower shielding tank and wherein an upper portion of said lower shielding tank communicates with upper portions of other shielding tanks.
 8. A wet-shield cryogenic fluid container as claimed in claim 7 wherein upper portions of all of said plurality of shielding tanks have vents to allow spent gases to be vented therefrom.
 9. A wet-shield cryogenic fluid container as claimed in claim 1 wherein each of said tanks comprises elongated, flat tubes which are attached to one another in a side-by-side relationship and which are interconnected with one another by pipes located at the ends of said tubes.
 10. A wet-shield cryogenic fluid container as claimed in claim 9 wherein a lower shielding tank covers the lower portion of said inner-shell, and right and left upper shielding tanks respectively cover right and left upper portions of said inner-shell.
 11. A wet-shield cryogenic fluid container as claimed in claim 10 wherein said manifold assembly includes means for filling said plurality of shielding tanks from a single inlet tube.
 12. A wet-shielding cryogenic fluid container as claimed in claim 11 wherein said inlet tube communicates with a lower portion of a lower shielding tank and an upper portion of said lower shielding tank communicates with upper portions of other shielding tanks.
 13. A wet-shield cryogenic fluid container as claimed iN claim 12 wherein upper portions of all of said plurality of shielding tanks have vents to allow spent gases to be vented therefrom. 